textproduct: Albany

SYNOPSIS

Mostly cloudy but milder weather is expected today along with isolated to scattered rain showers. A cold front crosses the region tonight bringing blustery and colder weather for the remainder of the week along with lake effect snow showers. Heavy snow accumulations are expected across portions of the Adirondacks and possibly the Mohawk Valley. Drier weather returns by Saturday with high pressure returning before another system brings mixed rain and snow on Sunday.

SHORT TERM /THROUGH FRIDAY NIGHT/

Key Messages:

- A period of lake effect snow is expected later Thursday through Friday across portions of the Adirondacks and Mohawk Valley. Snowfall amounts of 6 to 12 inches are expected in the most persistent lake effect bands.

- A Lake Effect Snow Warning is in effect for Northern Herkimer and Hamilton County from Thursday afternoon into Friday night. A Winter Storm Watch remains in effect for Southern Herkimer County from Thursday Afternoon into Saturday Morning.

- Wind gusts between 30 and 40 mph on Thursday and Friday could lead to areas of blowing and drifting snow.

Discussion:

A warm front is lifting northward across the region this morning. The steadiest rain has departed to the east but favorable upper level lift within the warm sector will support additional isolated to scattered showers through this afternoon. Later this afternoon into the evening hours, a cold front will approach from the west. Along with front, another area of rain showers will cross parts of the area. There could be some brief periods of more moderate rain with this activity. Pending surface temperatures, precipitation could change over to snow across parts of the southwest Adirondacks before ending. Despite a mostly cloudy day, temperatures should reach the 50s to lower 60s for many areas, except in the upper 40s to around 50 across the Adirondacks, which is about 10-15 degrees above normal high temperatures for late November.

As the front crosses, upper level troughing builds into the region for the remainder of the week with a nearly vertically stacked low pressure system positioned across Quebec. Moist, cyclonic flow and the arrival of colder air will support the development of lake effect snow. The wind flow will start out southwesterly which will result in mostly dry weather to start Thanksgiving Day with bands oriented west of our CWA. By the afternoon, the flow will become more west to west-southwesterly which will shift the bands slightly south and eastward into parts of the Adirondacks. Some fragments of the lake effect bands off Erie could reach parts of the Mohawk Valley by the afternoon hours as well. By Thursday night into Friday, the passage of an upper level shortwave will shift the winds to a more west-northwest to northwesterly direction for Friday. This will shift the band southward and become oriented across portions of the Mohawk Valley and eastern Catskills. Lake effect snow across the Adirondacks will then transition to upslope snow showers for Friday. There is some uncertainty with the overall placement of the Lake Ontario snow band on Friday. Two scenarios are in play which include the snow band oriented right over the NY Thruway corridor or just to the south. Where the band does set up, additional moderate to heavy snowfall accumulations are likely to occur due to the presence of moderate lake induced instability and a multi-lake connection extending all the way back to Lake Superior. Fragments of the snow band will likely extend into portions of the Hudson Valley with upslope snow showers across the southern Greens and Berkshires. High pressure building into the region on Saturday will gradually shut off the lake effect response.

In the most persistent lake effect bands, 6-12 inches of snow is expected. Confidence in these amounts was high enough to upgrade Northern Herkimer and Hamilton Counties to a Lake Effect Snow warning on this shift, plus with the lake effect snow starting on Thursday. Due to decreased confidence on the overall orientation of the snow band across the Mohawk Valley and likely not beginning until early Friday, have maintained the Winter Storm Watch for Southern Herkimer County. Where the band does sets up, warning level snowfall is likely to fall. Pending the orientation of the snow band, additional Winter Weather headlines may be needed later in time for Fulton, Montgomery and/or Schoharie counties.

Outside of the lake-effect it will be blustery and colder with highs in the lower 30s to lower 40s on Thanksgiving Day and upper 20s to upper 30s on Friday. Wind gusts between 30-40 mph later this week (strongest on Friday) will add to the chill in the air and also lead to areas of blowing and drifting snow.

LONG TERM /SATURDAY THROUGH TUESDAY/

As mentioned above, surface high pressure and weak upper level ridging builds over the region to start the weekend. This will shut off the lake effect snow and result in a dry start to the weekend. It will remain on the chilly side with highs only in the mid-20s to upper 30s, but there will be less wind compared to the previous two days. Another low pressure system tracking across the Great Lakes will bring another round of precipitation for Sunday. With temperatures rebounding into the 30s and 40s, mixed rain and snow is expected with this system. Snow would be favored for higher elevations. The cold front associated with this systems passes through by late Sunday which could lead to a mainly dry start to next week with high pressure returning. However, another wave of low pressure may form along the front bringing the potential for additional precipitation by Tuesday or Wednesday of next week, pending the overall timing and track of this system.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

A warm front is located just south of the region. A cool and moist air mass at low levels is keeping plenty of low stratus around. Radar imagery continues to show some spotty showers around and observations have been showing areas of drizzle/mist around the area we well. The combination of all of this will continue to keep IFR/LIFR conditions for most sites into the morning hours. Although there may be brief improvements to MVFR at times, most of the time will be IFR/LIFR, with ceilings in the 400-900 ft range and visibility occasionally down around 1/2SM to 2SM thanks to mist/showers. Winds will be calm at KGFL/KPOU, but should be southerly around 5-10 kts for KPSF and KALB.

As the warm front starts to lift northward, there may be some improvement in ceilings by later this morning or the early afternoon hours. Ceilings should improve to 1200-1500 ft for most sites (although KGFL may continue to stay in the IFR range as the warm front may not totally lift north of there until late) by the early afternoon hours. Some occasional showers are still possible through the day, but activity looks fairly scattered to isolated in coverage and fairly brief, so will mainly address with a VCSH for now. Southerly winds will be 5 to 10 kts for all sites.

As a cold front approaches, there may be a broken line of heavier showers for this evening. This could have a quick bursts of lower visibility and ceilings within this activity just ahead of the front, mainly for KGFL, KALB and KPSF. Behind the front, ceilings will improve for all sites, as westerly winds allow drier air to move into the region. While KPSF may remain MVFR for a portion of the overnight, the other valley sites should see a return to VFR ceilings fairly quickly by late this evening with westerly winds around 10-15 kts. Any precip will end with the passage of the cold front this evening.

Outlook...

Thursday Night: Low Operational Impact. Breezy. Slight Chance of SHSN. Friday: Moderate Operational Impact. Windy With Gusts To 35 kts. Chance of SHSN. Friday Night: Low Operational Impact. Breezy. NO SIG WX. Saturday: No Operational Impact. NO SIG WX. Saturday Night: No Operational Impact. NO SIG WX. Sunday: Moderate Operational Impact. Chance of RA...SN. Sunday Night: Moderate Operational Impact. Chance of RA. Monday: Moderate Operational Impact. Chance of RA.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...Lake Effect Snow Warning from 4 PM Thursday to 1 AM EST Saturday for NYZ032-033. Winter Storm Watch from Thursday afternoon through Saturday morning for NYZ038. MA...None. VT...None.